Circuit breaker

ABSTRACT

A circuit breaker having an oil-filled tank of insulating material carrying the fixed breaker contact and a shaft by means of which an elongated movable contact may be pivoted into an upright position of circuit-closing engagement with the fixed contact.

United States Patent Inventors Minoru Barada;

Keiji Shimada, Shizuoka-ken, Japan 836,437

June 25, 1969 Jan. 26, 1971 K. K. Meidensha Tokyo, Japan July 5, 1968 Japan 43/47401 and 43/47402 Appl. No. Filed Patented Assignee Priority CIRCUIT BREAKER 7 Claims, 4 Drawing Figs.

US. Int. (I Field of Search.

200/150 .....H0lh 33/68 56] References Cited FOREIGN PATENTS 155,205 12/ 1 93 8 Austria ZOO/150C 850,075 8/1939 France ZOO/150C 1,296,779 5/1962 France ZOO/150C 418,570 10/1934 Great Britain..... ZOO/150C 510,473 8/ 1939 Great Britain ZOO/150C Primary Examiner-Robert S. Macon Attorney-Kelman and Berman ABSTRACT: A circuit breaker having an oil-filled tank of insulating material carrying the fixed breaker contact and a shaft by means of which an elongated rnoyable contact may be pivoted into an upright position of circuit-closing engagement with the fixed contact.

CIRCUIT BREAKER This invention relates to circuit breakers, and particularly to oil-filled circuit breakers suitable for high-voltage service.

Known contact breakers have movable contacts which travel in a straight, upright path, and must be of relatively great height to maintain adequate distances between the terminals connected to the contacts in all positions of the movable contact. Moreover, the electrode supports must be insulated from grounded structures such as an operating mechanism, and the known breakers are therefore of complex structure, large in size, and heavy.

The primary object of the invention is the provision of a contact breaker which is compact and light, and which consists of relatively few component parts, as compared to known breakers of similar capacity.

Another object is the provision of a circuit breaker which requires only little oil, and has a relatively low and narrow supporting structure for the electrodes.

Other objects and the attendant advantages of the invention will become apparent from the following description of a preferred embodiment when considered in conjunction with the accompanying drawing in which:

FIG. 1 shows a circuit breaker assembly of the invention in front elevation;

FIG. 2 shows the apparatus of the invention in side elevation;

FIG. 3 shows a portion of the apparatus of FIG. 2 in side elevational section; and

FIG. 4 illustrates a portion of the apparatus of FIG. 2 in a different operational position.

The apparatus shown in FIG. l'consists of three circuit breakers of a three-phase electric system arranged on the housing 25 of a common operating mechanism. The three circuit breakers are identical, and only one will be described hereinafter.

As is best seen in FIG. 3, the circuit breaker has a tank of oil-resistant insulating material which consists of a lower portion 1 and an upper portion 6, the two portions being connected by respective flanges 7, 8, and nuts and bolts 9. The tank is approximately rectangular in plan section and in elevational section, its depth being substantially greater than the width, but only a fraction of the height.

An apertured partition 5 extends horizontally near the top of the lower tank portion 1 and divides the tank interior into a lower arc extinction chamber and an upper oil separation chamber. A body of oil 2 fills the extinction chamber and extends into the separation chamber through the openings in the partition 5.

A fixed contact member 3 passes through the front wall of the lower tank portion 1 just below the partition 5. Its inner portion is blade shaped, and its outer portion is threaded. It is secured on the tank wall by a nut 14. A movable contact member 4 is vertically elongated in the circuit-closing position of FIG. 3, and its upper end engages the fixed contact member 3. Its lower end is fastened to a shaft 22 of conductive material by a screw 23, the shaft being journaled in the two sidewalls of the lower tank portion 1 in sealing engagement.

Bosses 17, 26 having threaded blind bores respectively project from the front and rear walls of the tank portion 1. A vent 11 on the tank portion 6 permits gas to escape from the separation chamber and the oil in the tank to be replenished. The tank may be drained by removal of a plug 35 from the lower portion 1. A sight glass 34 indicates the oil level.

As is best seen in FIG. 2, the tank is attached to the housing 25 by a screw 27 entering the bore in the boss 26 and by a supporting bar 15 of insulating material whose upper end is suspended from the threaded end of the fixed contact member 3 and fastened by a nut 16. Another nut on the threaded end provides a terminal which may be tightened on a conductor. The central portion of the bar 15 is attached to the tank portion 1 by a screw 18 (FIG. 1) engaging the bore in the boss 17. The lower end of the bar 15 is attached to two threaded studs on the housing by nuts 28.

The end portion of the shaft 22 outside the tank portion 1 is square in cross section and is provided with a fixed radial arm 29. A connecting bar 30 of insulating material is secured to the arm 29 by a pivot pin 31 and to an operating element 32 of the mechanism in the housing 25, not otherwise shown.

As is apparent from joint consideration of FIGS. 1 and 2 or 4, the screw 18 also holds a plate 19 equipped with a threaded terminal post and nut 21 for another conductor. A flexible strap 24 attached to the shaft 22 by a screw 23 outside the tank portion 1 conductively connects the shaft to the plate 19.

When the bar 30 is pulled toward the right, as viewed in FIG. 2, by the operating mechanism, the shaft 22 and the movable contact member 4 are pivoted clockwise into the position seen in FIG. 4, and the free end of the contact member 4 is disengaged from the fixed contact member 3. When the terminals 20, 21 are connected to a current source, an arc is formed between the free end of the fixed electrode member 3 and the nearest part of the movable electrode member 4 in a direction which is always perpendicular to the direction of elongation of the movable contact member.

The oil in the arc extinction chamber is partly decomposed by the arc to form a gas, and the expanding mixture of oil and gas moves rapidly through the apertured partition 5 into the oil separation chamber.

The arc is extended, cooled, and ultimately broken by the rushing fluid. The mixture of oil and gas is separated into the components in the oil separation chamber, and the gas is released from the vent 11.

It is an advantage of the illustrated circuiLbreaker that the tank consisting of insulating material can be mounted directly on the grounded housing 25 of the operating mechanism, thereby avoiding the use of insulators. The spacing of the terminals 20, 21 is relatively small because of the pivotal movement of the electrode member 4, as compared to known breakers having contacts which move linearly toward and away from a fixed contact member. The width of the tank in the axial direction of the shaft 22 can be made quite small, permitting the three breakers of a three-phase arrangement to be mounted close to each other.

Because the blade-shaped fixed contact member is elongated horizontally and the movable contact member elongated vertically at the moment of interrupting their engagement, the electromagnetic force developed by the resulting arc acts upwardly toward the partition 5 and assists in quickly extinguishing the arc.

The several features enumerated above make it possible to make the circuit breakers of the invention compact and light in weight, "and they reduce the cost of manufacturing the breakers as compared to known breakers of similar capacity. The breakers of the invention can also be operated with little power.

While the invention has been described with reference to a preferred embodiment, it is not limited to the example chosen for the purpose of the disclosure since many changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

1. A circuit breaker comprising, in combination:

a. a tank of insulating material adapted to contain oil;

b. an apertured partition dividing the interior of said tank into an oil separation chamber and an arc extinction chamber;

c. mounting means for mounting said tank in a mounted position in which said partition extends horizontally, said separation chamber being above said extinction chamber;

(1. a fixed contact member mounted in said extinction chamber on said tank;

e. a shaft journaled in said tank and having a first axial portion outside said tank and a second axial portion in said extinction chamber;

f. a movable contact member attached to said second axial portion for angular movement with said shaft toward and away from a circuit-closing position of current-transmitting engagement with said fixed contact member;

g. operating means connected to said first axial portion for angularly moving said shaft; and

h. two terminals spacedly mounted on said tank and conductively connected to said fixed contact and to said shaft respectively.

2. A circuit breaker as set forth in claim 1, wherein said movable contact member is elongated, one longitudinal end portion thereof being fastened to said shaft, and the other longitudinal end portion engaging said fixed contact member in said position of the movable contact member.

3. A circuit breaker as set forth in claim 1, said movable contact member being vertically elongated in said position thereof when said tank is in the mounted position.

4. A circuit breaker as set forth in claim 1, wherein said tank is substantially rectangular in plan section, having a width in the direction of the axis of said shaft much smaller than the depth thereof at right angles to said width.

5. A circuit breaker as set' forth inclaim 4. wherein said fixed contact member is elongated in a horizontal direction when said tank is in the mounted position thereof, said movable contact member being elongated in a vertical direction when in said circuit closing position, a longitudinally terminal portion of said movable contact member downwardly spaced from said movable contact member being fastened to said shaft.

6. A circuit breaker as set forth in claim 5, wherein said fixed contact member has a blade-shaped portion in said extinction chamber and another portion outside said tank.

7. A circuit breaker as set forth in claim 1, further comprising a body of oil filling said extinction chamber and extending into said separation chamber through the apertures in said partition. 

1. A circuit breaker comprising, in combinaTion: a. a tank of insulating material adapted to contain oil; b. an apertured partition dividing the interior of said tank into an oil separation chamber and an arc extinction chamber; c. mounting means for mounting said tank in a mounted position in which said partition extends horizontally, said separation chamber being above said extinction chamber; d. a fixed contact member mounted in said extinction chamber on said tank; e. a shaft journaled in said tank and having a first axial portion outside said tank and a second axial portion in said extinction chamber; f. a movable contact member attached to said second axial portion for angular movement with said shaft toward and away from a circuit-closing position of current-transmitting engagement with said fixed contact member; g. operating means connected to said first axial portion for angularly moving said shaft; and h. two terminals spacedly mounted on said tank and conductively connected to said fixed contact and to said shaft respectively.
 2. A circuit breaker as set forth in claim 1, wherein said movable contact member is elongated, one longitudinal end portion thereof being fastened to said shaft, and the other longitudinal end portion engaging said fixed contact member in said position of the movable contact member.
 3. A circuit breaker as set forth in claim 1, said movable contact member being vertically elongated in said position thereof when said tank is in the mounted position.
 4. A circuit breaker as set forth in claim 1, wherein said tank is substantially rectangular in plan section, having a width in the direction of the axis of said shaft much smaller than the depth thereof at right angles to said width.
 5. A circuit breaker as set forth in claim 4, wherein said fixed contact member is elongated in a horizontal direction when said tank is in the mounted position thereof, said movable contact member being elongated in a vertical direction when in said circuit closing position, a longitudinally terminal portion of said movable contact member downwardly spaced from said movable contact member being fastened to said shaft.
 6. A circuit breaker as set forth in claim 5, wherein said fixed contact member has a blade-shaped portion in said extinction chamber and another portion outside said tank.
 7. A circuit breaker as set forth in claim 1, further comprising a body of oil filling said extinction chamber and extending into said separation chamber through the apertures in said partition. 